Figure 3. Time series of SMB components, integrated over the ice sheet including ice shelves, for the period 1979–2010 {all in Gt y^-1}. Snowfall (black solid line) is shown on the left axis, together with the SMB (bars), the other components are shown on the right axis.

Received 17 January 2012; accepted 21 January 2012; published 21 February 2012.

Abstract: [1] A new, high resolution (27 km) surface mass balance (SMB) map of the Antarctic ice sheet is presented, based on output of a regional atmospheric climate model that includes snowdrift physics and is forced by the most recent reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF), ERA-Interim (1979–2010). The SMB map confirms high accumulation zones in the western Antarctic Peninsula (>1500 mm y^-1) and coastal West Antarctica (>1000 mm y^-1), and shows low SMB values in large parts of the interior ice sheet (<25 mm y^-1). The location and extent of ablation areas are modeled realistically.

The modeled SMB is in good agreement with ±750 in-situ SMB measurements (R = 0.88), without a need for postcalibration. The average ice sheet-integrated SMB (including

UPDATE: One of my readers emailed me today to say that I had left off a minus sign in the last paragraph where it says: 3+/-2 Gt/y^-2 which should read –3+/-2 Gt/y^-2 instead. Corrected, my apology for the error, which originated in this original email from Dr. Leif Svalgaard:

That missing minus sign doesn’t change the conclusion in the paragraph of “We found no significant trend in the 1979–2010 ice sheet integrated SMB components, “ but some alarmist types are apparently all atwitter and looking for nefarious motives. What is typical of that criticism, is that it’s just another coward saying nasty things without the courage to put his/her name behind the words of criticism.

Here’s the fun part, you can open up the PDF that Leif Svalgaard provided here. Then go to paragraph [15] and highlight the relevant text listed above that this blogger and the Tamino crowd are all upset about, and then paste it into notepad or the comments box below and watch the minus sign disappear!

Apparently it is some oddly formatted character they used, and gets stripped on copy/paste, which is why Dr. Svalgaard accidentally sent it to me that way. Another “evil and devious skeptic plot” bites the dust. – Anthony

That is a 31 year period that the paper evaluated. So those climate scientists who say the minimum climate period required for statistically significant evaluation is 30 yrs must stay mute that the period evaluated is too short.
John

When will these people learn , your facts are worth nothing, the model is all.
I wish people would stop doing actual science and taken measures of physical things there is no need , all truth is found in the models ‘ For is it not the first commandment of climate scene ‘ when reality and the models differ in value , it is reality which is in error ‘ /sarc off

You left the minus sign off of the 3 in your last sentence. It should read:
“The estimated SMB trend, integrated over the ice sheet, equals -3 +/- 2 Gt y^(-2).”
I’ll assume it was a cut and paste error because of the fonts used. It happened to me just now when I pasted it in.

The scientific credibility of this study is certainly bolstered by the fact that “the modeled Surface Mass Balance is in good agreement with ±750 in-situ SMB measurements” (a.k.a. empirical data). However, I still felt a slight shudder when I read “the map is based on output of a regional atmospheric climate model”.
Let’s hope this proves to be reproducible.

Surface Mass Balance (SMB) is not the same thing as mass balance.
Mr. Watts, I believe that you are misinterpreting what this paper says.
For reference, the lead author is also a co-author on the 2011 GRL paper, “Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise”. Monaghan is also a c-author on this paper. If you read this paper ( http://ess.uci.edu/researchgrp/velicogna/files/rignot_etal_grl2011.pdf ) you may better understand the difference between mass balance and surface mass balance (SMB), which is clearly discussed on the first page.

You might want to check the sign of your ‘money quote’ against the paper.
You might want also to refresh your memories of the definition of mass balance (hint – check the units).
You might want also to compare this result with the IPCC projection.

Remember the old line about the MWP being “not global … only a localized NH fluctuation”?
Weeeellll, that’s been shown false (eg the data at co2science.org) but it begins to look as if it applies to the modern warming period.

In case my above comment was not clear enough:
Mass balance of Antarctica = SMB (water in) less perimeter loss (water out)
So the observation that SMB is more or less constant over the past 30 years says nothing about the perimeter loss, or about the mass balance of Antartica.
For a more complete discussion, including a comparison of two methods of measuring mass balance, I refer you to:
“Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise”
E. Rignot, I. Velicogna, M. R. van den Broeke, A. Monaghan, and J. Lenaertshttp://ess.uci.edu/researchgrp/velicogna/files/rignot_etal_grl2011.pdf

Assessment of the data and techniques suggests overall Antarctic Ice Sheet mass balance ranging from growth of 50 Gt yr–1 to shrinkage of 200 Gt yr–1 from 1993 to 2003. As in the case of Greenland, the small number of measurements, lack of agreement between techniques, and existence of systematic errors that cannot be estimated accurately preclude formal error analyses and confidence limits. There is no implication that the midpoint of the range given provides the best estimate. Lack of older data complicates a similar estimate for the period 1961 to 2003. Acceleration of mass loss is likely to have occurred, but not so dramatically as in Greenland. Considering the lack of estimated strong trends in accumulation rate, assessment of the possible acceleration and the slow time scales affecting central regions of the ice sheets, it is reasonable to estimate that the behaviour from 1961 to 2003 falls between ice sheet growth of 100 Gt yr–1 and shrinkage of 200 Gt yr–1.

(of course, that is complicated by this model being *surface* mass balance, but that distinction is going to go right over your heads).

@ Louis Hooffstetter:
Agree strongly with:
” I still felt a slight shudder when I read “the map is based on output of a regional atmospheric climate model”
If a reasonable scepticism is warranted for our current modelling of other complex climate phenomena, it should be here as well. We don’t want to cherrypick our models and undermine the value of broad-based scientific scepticism.

Brian H says:
Note that the final number given is for an increase, though it is not statistically significant.
If it had been a decrease, that would have been the title of the paper and the headline of the press release. “Not statistically significant” would have been buried in the fine print and qualified with “but only just”.

BCC says:
February 20, 2012 at 2:57 pm
The paper you referenced quotes an SMB trend of -5.5 +/- 2 Gt/yr/yr
This one quotes an SMB trend of -3.0 +/- 2 Gt/yr/yr.
In other words, pay your money and select whichever figure best suits your view of the world.
Climate “science” in a nutshell……

Okay, the modeled SMB is in good agreement with ±750 in-situ SMB measurements, so that’s some validation. But If it’s a model, how can it “confirm” anything? Shouldn’t this just be a “yay, we’ve got a more realistic model!” sort of hype?

This argument is silly because most of the continent is simply too cold for significant melting.Most of it stays below freezing the entire year.
Just along some shorelines and small areas of the west Antarctica get above freezing for short time periods maybe reach into the 40’s.Not long enough for the feeble above freezing air to penetrate hundreds of feet thick of snow and ice.
A little logic will go a long way here……

A new, high-resolution surface mass balance map of Antarctica
(1979–2010) based on regional atmospheric climate modeling
…..funded by Tipper Gore
dang computer games…you can make them do and say anything

BBC says:
“Mass balance of Antarctica = SMB (water in) less perimeter loss (water out)
So the observation that SMB is more or less constant over the past 30 years says nothing about the perimeter loss, or about the mass balance of Antartica.”
Since perimeter ice area is actually UP over the satellite record I would suggest this paper in fact does say something about mass balance. Though I too am sceptical of models.
see ice datahttp://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.antarctic.png

“”William M. Connolley says:
February 20, 2012 at 3:12 pm (of course, that is complicated by this model being *surface* mass balance, but that distinction is going to go right over your heads).””
The fact that the IPCC is unable to confirm or deny growth or shrinkage, that distinction between this empirical data of this paper and the IPCC uncertainty is probably going to go right over your head.
Of course people like J. T. M. Lenaerts, M. R. van den Broeke, W. J. van de Berg, E. van Meijgaard,and P. Kuipers Munneke wouldn’t come anywhere near your intellectual prowess.
William you are a legend in your own mind.

BCC
The Antarctic Ice Sheet contains 30 million cubic kilometers (7.2 million cubic miles) of ice.
One gagatonne of water has a volume of one billion cubic meters, or one cubic kilometer.
36.3 Gt/y-1 or 0.000121%.
So in 826,000 years time it may be that there is only one ice-cube sized piece of ice left. Unless on of the 7 ice-ages that will happen in this time, do not replenish the ice.
Measuring a rate at +/- 10^-6 is rather good.

@William M. Connolley
======================
“With rising global temperature, GCMs indicate increasingly positive SMB for the Antarctic Ice Sheet as a whole because of greater accumulation (Section 10.6.4.1). For stabilisation in 2100 with SRES A1B atmospheric composition, antarctic SMB would contribute 0.4 to 2.0 mm yr–1 of sea level fall (Table 10.7). Continental ice sheet models indicate that this would be offset by tens of percent by increased ice discharge (Section 10.6.4.2), but still give a negative contribution to sea level, of –0.8 m by 3000 in one simulation with antarctic warming of about 4.5°C (Huybrechts and De Wolde, 1999).”http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-7-4-4.html
Connolley appears to cite the parts of the IPCC that are convenient to his argument but doesn’t cite the parts that are inconvenient.

As much as it sorely grieves me to have to admit it, in this case Connelly and others are correct. This paper doesn’t say what you think it does people. That said, it’s yet another paper based almost purely on modelling, so make of that what you will 😉

Hey, poster identifying as “William Connelley”, is this you?
“[Connelley’s] career as a global warming propagandist has now been stopped, following a unanimous verdict that came down today through an arbitration proceeding conducted by Wikipedia. In the decision, a slap-down for the once-powerful Connolley by his peers, he has been barred from participating in any article, discussion or forum dealing with global warming. In addition, because he rewrote biographies of scientists and others he disagreed with, to either belittle their accomplishments or make them appear to be frauds, Wikipedia barred him — again unanimously — from editing biographies of those in the climate change field.”http://tinyurl.com/35ajlkr
Just wondering. 😉

@LC
Ok, so we did trust science for a few minutes, but then it turns out the science we just agreed with disagrees with our opinion, so therefore we stopped trusting science again, and vehemently disagree with the paper?
Did I get that right?
(Censorship rocks!)
[Reply: Read the site Policy. You are threadbombing under numerous articles. This site does not censor different scientific points of view. We snip or delete posts that violate our written Policy. If that bothers you, please move on. And the next time you post “censorship rocks” or anything similar, I’ll give you what you’re wishing for. ~dbs, mod.]

LC says:
February 20, 2012 at 4:29 pm
“As much as it sorely grieves me to have to admit it, in this case Connelly and others are correct. This paper doesn’t say what you think it does people. That said, it’s yet another paper based almost purely on modelling, so make of that what you will ;)”
==================================================
What do you think Connelly wrote that requires your endorsement? He seems to have done two things here (1) Cite the IPCC where they point out that measurement of ice balance is deeply uncertain. And (2), everyone here is stupid except for him. 😉

The SMB map confirms high accumulation zones in the western Antarctic Peninsula (>1500 mm y^-1) and coastal West Antarctica (>1000 mm y^-1), and shows low SMB values in large parts of the interior ice sheet (<25 mm y^-1).
There isn’t much dispute that the western Antarctic Peninsula has warmed over this period with substantial peripheral ice melt. This study shows it snowed a lot more when the western Antarctic Peninsula warmed. Unsurprising as the warming results from increased oceanic influence. The increased snowfall will doubtless result in future glacial advances.
All in all, it points to a decadal oceanic cycle mainly determining western Antarctic Peninsula ice mass.

Connolley appears to cite the parts of the IPCC that are convenient to his argument but doesn’t cite the parts that are inconvenient.

Actually, the part that you cite provides even further support for points that Connolley was making, including the fact that there is a distinction between the total mass balance and the surface mass balance and that the surface mass balance is EXPECTED to increase. You also seem to have left out the paragraph following the one that you did quote, perhaps because it is a bit inconvenient to you:

However, discharge could increase substantially if buttressing due to the major West Antarctic ice shelves were reduced (see Sections 4.6.3.3 and 10.6.4.2), and could outweigh the accumulation increase, leading to a net positive antarctic sea level contribution in the long term. If the Amundsen Sea sector were eventually deglaciated, it would add about 1.5 m to sea level, while the entire West Antarctic Ice Sheet (WAIS) would account for about 5 m (Vaughan, 2007). Contributions could also come in this manner from the limited marine-based portions of East Antarctica that discharge into large ice shelves.

@Smokey
Urban Dictionary: “”Threadbombing” is posting an image (or images) with superimposed text in a forum thread; usually to illustrate a point. Often, the “threadbomb” conveys a humorous message of disdain towards the original poster or the entire thread.”
WTF?

boston12gs says:
February 20, 2012 at 4:33 pm
Hey, poster identifying as “William Connelley”, is this you?
=============================================
..one and the same
Wikipedia Topic-Bans Global Warming Activist William Connolley, aka ‘Stoat’
By: Bradley Fikes — October 16th, 2010
Wikipedia is supposed to be a source of information, not propaganda. But William M. Connolley, who blogs under the name Stoat, has repeatedly abused his administrator position at Wikipedia to bias climate change-related articles to reflect his global warming activism.
But no more. After extensive run-ins with Connolley, Wikipedia has banned him from participating in climate change articles.
Since CAGW (Catastrophic Anthropogenic Global Warming) supposedly has so much evidence on its side, it’s remarkable how vehemently Connolley fought against letting Wikipedia readers read neutral articles that include the views of skeptics. His deceptive conduct was deeply unethical.
Watts Up With that points that that in addition to Connolley, other administrators on both sides of the global warming issue have been sanctioned. At least one CAGW-skeptical administrator says he was sanctioned for kicking up a fuss about the pro-CAGW bias.
At least the net result is a gain for fair editing, since Connolley was by far the most active in shamelessly inserting his bias into Wikipedia’s global warming articles.
Connolley’s pro CAGW campaign extended over years. I hope that Wikipedia speeds up its cumbersome bureaucratic process so that future offenders can be dealt with more swiftly.http://www.nctimes.com/app/blogs/wp/?p=11266

For those whining about it being a model based study, quoting from the conclusions……“Without additional calibration, the modeled SMB agrees very well with 750 in-situ SMB observations….
For those worrying about what this paper actually states, look at figures 3 & 4 and understand the different scaling. You can visualize the math from there. Then also ask yourselves, is sublimation consistent with the CAGW hypothesis? Further, look again at figure 3. The only graphed component which has a discernible trend is melt!!……. which way is that going? Is that consistent with the CAGW hypothesis?

With all the attacks accumulating on William Connoley, few people have yet realized the substantial error in the post by Anthony Watts (or at the very least, that it gives a misleading impression of what is happening to Antarctica to people who don’t understand the terminology). It only takes a slight amount of courage or honesty for everyone to admit this, and does not depend on how much you like the IPCC, Connoley, Michael Mann, the climategate e-mails, or whatever else.
The total mass budget involves estimating the difference between surface mass balance (input) and perimeter fluxes (output). That said, Antarctica is almost certainly losing ice (contributing to sea level) in its net effect. The IPCC 2007 report is rather outdated on this subject and observational ability has improved tremendously since that time. See for example Rignot et al (2011, GRL); Velicogna, I., (2009, GRL), and there are large regional changes, especially in the Antarctic Peninsula & West Antarctica that are changing rapidly (e.g., Cook and Vaughan, 2010; Ivins et al., 2011). It would be nice to see some WUWT summaries of these papers…

yawn,
You’re a noob here, so I’ll explain it for you. On this site threadbombing is making multiple comments that have little or no redeeming purpose, other than to monopolize the conversation with science-free, fact-free nonsense from site pests. Just like most of your comments, in fact.

A few observations on the various papers cited here:
“We found no significant trend in the 1979–2010 ice sheet integrated SMB components, which confirms the results from Monaghan et al. [2006].”
The following is not a surprise and consistent with “Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise” – http://ess.uci.edu/researchgrp/velicogna/files/rignot_etal_grl2011.pdf
The conclusion of this paper s that “The magnitude of the acceleration suggests that ice sheets will be the dominant contributors to sea level rise in forthcoming decades, and will likely exceed the IPCC projections for the contribution of ice sheets to sea level rise in the 21st century [Meehl et al., 2007].”
The implication being that even if SMB is relatively stable, MB is decreasing. This presumably implies that there is some empirical support for an increase in ice calving. What else could it be?
The conclusion reached by Rigno et. al, needless to say, is the opposite of the expectation of IPCC AR4, where GCM modelling is expecting to see an increasing SMB trend.
The main game in town is SMB, not MB. If MB is accelerating but SMB has no trend, then it seems difficult to reconcile this with GCM atmospheric modelling. Now if someone disagrees, I’d be interested in a different point of view. However, I would seek clarification on how MB acceleration can be explained in terms of AGW theory when there is no observable SMB trend.
In summary:
Rigno et al agrees with Lenaerts et al, on no trend in SMB but reaches the opposite conclusion of the IPCC AR4 report. On the other hand IPCC AR4 expected to see an increasing SMB trend, according to GCM’s, which is not observed by Lenaerts el al, either. So if the GCM’s are correct, it just hasn’t happened (yet) as predicted.
So you have a bunch of authorities who all basically disagree with each other in one way or another where it matters, which is sea level rise attributable to GW. Such is climate science.

Jeeeze, it’s almost like that whole “Greenhouse Effect” thingy is only working inside the computer models. What’s an honest climate scientist to do? I guess you could claim that the missing heat is lost in the measurement errors. That usually works when something I design doesn’t work as I predicted it would, Ha, Ha….
Maybe the NULL HYPOTHESIS (i.e. the climate varies naturally and the GHE has no impact on the average temperature) is correct ????
After several decades looking for the signature of the GHE all I’m hearing is EXCUSES, and of course name calling and requests for more tax dollars to study the “problem”.
Cheers, Kevin (denier)

This thread and the comments with the abstract are not correct. This was not an assessment of mass balance of the ice sheet. It was modelling the surface mass balance. These are two different things.
It is idiotic to jump on a high horse and confound the two when they’re very different. Shame on everyone here for not reading the article or taking the time to learn anything at all on the subject before commenting.

Also for the record, this is creating a dataset that goes into complete mass balance surveys such as Rignot et al 2011. It is one component of Mass Balance for the whole ice sheet.
Antarctic Mass Balance = Ice Input – Ice Output
Ice Input comes through the SMB and the SMB is nearly 0 so the Antarctic Mass Balance then equals 0 minus ice outputs through calving and accelerating glaciers (Pine Island Glacier for Example).
Rignot et al. 2008 and Rignot et al. 2011 use INSAR Flux budget method to calculate the Mass Balance of the ice sheet by measuring the Output and comparing it to the SMB. They find losses are huge because of dynamic ice loss from accelerating glaciers.

Uh-oh: http://dotearth.blogs.nytimes.com/2012/02/20/peter-gleick-admits-to-deception-in-obtaining-heartland-climate-files/
Peter Gleick Admits to Deception in Obtaining Heartland Climate Files
By ANDREW C. REVKIN
Peter H. Gleick, a water and climate analyst who has been studying aspects of global warming for more than two decades, in recent years became an aggressive critic of organizations and individuals casting doubt on the seriousness of greenhouse-driven climate change. He used blogs, congressional testimony, group letters and other means to make his case.
Now, Gleick has admitted to an act that leaves his reputation in ruins and threatens to undercut the cause he spent so much time pursuing. His summary, just published on his blog at Huffington Post, speaks for itself. You can read his short statement below with a couple of thoughts from me:

@Robert says:
Surface Mass Balance is different from total Mass Balance.
Dynamic loss is glaciers accelerating which is where most ice sheets lose their ice. This paper does not look at that. Noobs…
=========================
Obviously we’re all noobs here Robert. But since you’re a clever fellow, could you explain the relationship between MB, SMB and GCM modelling? In relation to AGW, the main game in town is, obviously, SMB and not MB.
(How’s that for packing a lot of acronyms into one sentence? 😉

Yawn: We don’t distrust science at all. We distrust studies if and when there is reason to do so. That Yawn is what science should do. If it can’t hold up to scrutiny then it isn’t science. If you have some meaningful reason to doubt this study, then your comments will be appreciated here.

If the grounding line remains constant then SMB = MB.
If the point where the ice floats rather than sitting on bedrock (even if below sea level) moves toward shore then it is possible to have a positive surface mass balance while the overall mass balance is negative.
The paper discussed in this WUWT post is about SMB only.

There tends to be an awful lot of confirmation bias in reports like this, with people leaping onto anything that may confirm their views.
I suggest something simple – posts like this should always contact one of the paper’s authors to ask what it really means before doing a write-up. This would eliminate a great deal of baseless speculation. I do not know the difference between MB and SMB, so I will not comment, but it is clear that a lot of other people also do not know, but are willing to comment anyway.

Robert wrote;
“This was not an assessment of mass balance of the ice sheet. It was modeling (sic) the surface mass balance. These are two different things.”
Agreed, however the surface of the ice is the only place where the interactions of sunlight, warm air and warm water can possibly melt the ice and thus reduce its volume. So, if it is not being observed there how exactly is the rest of the ice volume decreasing? Indeed the GHE Hypothesis specifically states that “extra energy” from the “effect” warms the SURFACE. Are you asserting that IR “backradiation” penetrates deeply into the ice and melts it from below? X-rays might do that, but I strongly doubt that relatively unenergetic IR radiation posses this additional magic trait. However it appears a pretty tricky beast that can cause warming for decades and then stop working for additional decades.
If I try to drill a hole through a 10 foot thick concrete wall and my drill bit fails to penetrate the surface by more than 0.01 inch does the remaining 9.99 foot of hole magically drill itself?
Noobs, indeed, please see my reference to name calling.
Cheers, Kevin (recently upgraded to a denying noob)

Will Nitschke says:
February 20, 2012 at 6:00 pm
“In relation to AGW, the main game in town is, obviously, SMB and not MB.”
Not true. Dynamic ice losses are due to warming oceans causing grounding line retreat subsequently accelerating glaciers and carrying more ice to the sea. Warming oceans is definitely related to AGW. Noob.

Silly rabbit! The fact is in the other hat!
It’s not mass, it’s area that’s important. And area has been increasing rapidly while mass holds steady, which is a sign of the flattening of the Antarctic. Yes, the world will soon be following this flattening trend until the whole thing is flat. And then trade and commerce will be paralyzed because ships will no longer be able to sail around the world. Woe be to us all!

Robert says:
Not true. Dynamic ice losses are due to warming oceans causing grounding line retreat subsequently accelerating glaciers and carrying more ice to the sea. Warming oceans is definitely related to AGW. Noob.
================================
Did you make that up or can you cite a paper for that claim? Just curious. I don’t have a problem if you write, “I speculate that it might be caused by…” but Warmists always post messages as if their proclamations were authoritative…
Also, since a number of Warmists here are arguing that SMB is irrelevant (when exactly the opposite is in fact true), and the basis of this claim is the paper by Rignot et al, and their analysis is based on data from 1992-2010, are they aware that if you remove the 1992 year there is probably no trend for the rest of the data? In fact, there is possibly mass balance gain as well? Would you consider an analysis robust if you toss 1 year out of 12 from the data set and this reverses the conclusion?
(With Warmists, you have to be very careful about not what they argue, but what information they leave out of the discussion…)

Anything is possible: The point isn’t about the trend of SMB, or whether it’s up or down; the point is that Mr. Watts is interpreting this paper to mean that there is no (significant) trend in the mass balance of the Antarctic. The paper says no such thing. Also: Other recent papers (some of which are co-authored by the authors of this paper) say quite the opposite.
In conclusion: This isn’t about cherry picking, this is about either misunderstanding, or choosing to misrepresent, the findings of this paper.
DocMartyn: Among other things, the 36.3 Gt/y you cite is actually 36 Gt per year PER YEAR (for Greenland + Antarctica). It’s an acceleration. So, your equation is wrong. Besides, we agree: There’s going to be ice in Antarctica for a long time to come. But problems arise if even only *some* of Antarctica melts.

Will Nitschke says:
February 20, 2012 at 7:12 pm
“When a glacier is in balance or flowing at its balance velocity, net mass will remain balanced. However, when a glacier accelerates while near or at its balance velocity, the outputs resultantly increase but the inputs do not, thereby shifting the glacier regime to one of negative mass balance or net ice loss. This situation is particularly important because accelerated ice flow is the key method through which the Antarctic ice sheets incur a net ice loss. Accelerations such as these occur through two primary mechanisms. The first of which is caused by surface melt water reaching the glacial bed causing basal lubrication therefore reducing the frictional forces at the bed and thus increasing ice flow (Bell 2008).
The second mechanism refers to when the forces at the downstream terminus of a glacier or ice stream are disturbed or altered. This can occur through removing buttressing ice shelves or by shifting the glacier’s grounding line (point where glacier ice reaches floatation). The presence of an ice shelf provides a longitudinal compressive force which slows the flow of ice streams. If removal of this compressive force occurs, velocity of ice streams increase. This has been observed directly by Scambos et al (2004) and Rignot et al (2004) through both visual observations (Scambos) and radar interferometry (Rignot).
In terms of a grounding line retreat, an inland shift of the grounding line causes less backpressure through increased calving and basal melting. This process results in increased glacier velocities and subsequent inland thinning as more ice is being pulled from the accumulation zone (Bell 2008). In a warmer climate, one would expect that surface melting would increase, making the first mechanism more likely, however because of Antarctica’s climate and the omnipresence of ice shelves and calving glaciers there, the second mechanism actually dictates the ice losses from Antarctica. Evidence has already been presented which supports the theory that it is warm ocean water in West Antarctica which is in actuality enabling this second mechanism (Shepherd, Wingham and Rignot, 2002).”
Shepherd, Wingham and Rignot’s article is called “Warm ocean is eroding West Antarctic Ice Sheet” GRL 2004

Will Nitschke says:
February 20, 2012 at 7:12 pm
Warm Ocean is Eroding West Antarctic Ice Sheet
Geophysical Research Letters
2004
Also see the following:
“This situation is particularly important because accelerated ice flow is the key method through which the Antarctic ice sheets incur a net ice loss. Accelerations such as these occur through two primary mechanisms. The first of which is caused by surface melt water reaching the glacial bed causing basal lubrication therefore reducing the frictional forces at the bed and thus increasing ice flow (Bell 2008).
The second mechanism refers to when the forces at the downstream terminus of a glacier or ice stream are disturbed or altered. This can occur through removing buttressing ice shelves or by shifting the glacier’s grounding line (point where glacier ice reaches floatation). The presence of an ice shelf provides a longitudinal compressive force which slows the flow of ice streams. If removal of this compressive force occurs, velocity of ice streams increase. This has been observed directly by Scambos et al (2004) and Rignot et al (2004) through both visual observations (Scambos) and radar interferometry (Rignot).
In terms of a grounding line retreat, an inland shift of the grounding line causes less backpressure through increased calving and basal melting. This process results in increased glacier velocities and subsequent inland thinning as more ice is being pulled from the accumulation zone (Bell 2008). In a warmer climate, one would expect that surface melting would increase, making the first mechanism more likely, however because of Antarctica’s climate and the omnipresence of ice shelves and calving glaciers there, the second mechanism actually dictates the ice losses from Antarctica. Evidence has already been presented which supports the theory that it is warm ocean water in West Antarctica which is in actuality enabling this second mechanism (Shepherd, Wingham and Rignot, 2002).
We should all now at least remotely understand that mass balance changes in Antarctica aren’t reliant on surface melting but rather depend on dynamic responses such as the 2nd mechanism.”

@BCC:
In conclusion: This isn’t about cherry picking, this is about either misunderstanding, or choosing to misrepresent, the findings of this paper.
======================
What if the heading of the post was changed to:
“New paper: A high-resolution surface mass balance map of Antarctica suggests “no significant trend in the 1979–2010 ice sheet. Inconsistent (to date) with IPCC global climate modelling.”
Would you be happier?
Also Mr Watts could add this disclaimer:
“While most studies relating to Mass Balance of the Antarctic continent remain uncertain and it is not possible to draw significant conclusions due to a high degree of inter annual variability, it should be noted that Rignot et al (2011) suggests otherwise; however, the linear trend in that paper is sensitive to the start date of the analysis, and therefore may not be robust.”
I would argue that if the heading was changed and the disclaimer was added, it would make the post more balanced. I think it’s always a good idea to qualify claims as much as possible.

@Robert:
Warm Ocean is Eroding West Antarctic Ice Sheet
=============================
Are we talking about the West Antarctic Ice Sheet or are we talking about MB and SMB of the Antarctic continent?
Because if I wrote a post that showed data that, say, sea level was dropping off the coast of Brisbane, I’m sure you would be furious with me, because it would only be fair to discuss global sea level change and not sea level change in Brisbane.
So now you point to a paper about the West Antarctic Ice Sheet which is pretty much the only coastal region that has seen any significant degree of warming. (With warming of around .5C over 50 years.) Keep in mind that most of the low latitude coast has an average temperature of -12C and the high latitude coast an average temperature of -17C. The Antarctic peninsula can get as warm as 1C on average at the summer peak. Just not sure how you extrapolate what’s happening in that region to the mass balance of the entire continent. I would not want to accuse you of cherry picking, but…

Will Nitschke:
“What if the heading of the post was changed to:
“New paper: A high-resolution surface mass balance map of Antarctica suggests “no significant trend in the 1979–2010 ice sheet. Inconsistent (to date) with IPCC global climate modelling.”
Would you be happier?”
No, because that title would be wrong. Trend in SMB is ***NOT*** the same thing as “trend in the … ice sheet.”
Ice sheets have mass. That mass, M, changes due to inputs (snow less ablation, etc., i.e. SMB), and outputs (flow of mass across the grounding line). dM/dT = SMB (expressed as GT/yr) – D (ice discharge, also GT/yr).
Direct measurements, via the GRACE satellites, show that DM/dt is negative and accelerating (see e.g. Rignot 2011). But these measurements tell you about dM/dt; they don’t (themselves) tell you about SMB and D.
Lenaerts et al measures SMB, based on regional modeling matched against empirical data. They find that d SMB / dT appears to be about zero (Rignot 2011 found a small insignificant negative trend; Lenaerts et al, 2012 shows an insignificant increase).
Meanwhile, D D/dt seems to be increasing (e.g. the discharge *rate* is increasing, so discharge is accelerating) D is “calculated from a time series of glacier velocity and ice thickness” (Rignot, 2011).
And here’s what the AR4 says on the matter (http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-6-4-1.html):
===
All studies for the 21st century project that Antarctic SMB changes will contribute negatively to sea level, owing to increasing accumulation exceeding any ablation increase (see Table 10.6). ***This tendency has not been observed*** in the average over Antarctica in reanalysis products for the last two decades (see Section 4.6.3.1)
===
*** emphasis mine
In sum: The Lenaerts paper does not contradict the findings that Antarctic ice sheets are losing mass (as indicated by the GRACE satellite DATA). Further, the Lenaerts paper does not contradict the AR4 report, which states that, while SMB is expected to increase, it hasn’t been observed to, yet.

@BBC:
You’ve basically repeated most of the points I already made, so I will focus on a couple of small things we disagree on. The problem with wanting to talk about MB instead of SMB is that AGW models make certain claims about SMB. It can’t say much about MB because the processes are not well understood in terms of measurement, modelling, etc. (Except in relation to SMB.) The change in MB is highly variable and uncertain. The paper you originally cited, covers only 12 years of data, and 11 of those 12 years don’t show much of a trend. To make matters worse, the high level of annual variability and the short time frame combined, makes any sort of linear trend extrapolation highly uncertain at best. This is why other papers that have looked at the same issue have been hesitant to draw conclusions. Plus your whole argument rests on citing this particular paper. Now, even if the paper was correct, what does it tell us about AGW? Very hard to say…
But the IPCC does reach some conclusions about SMB. It argues that there should be a positive SMB trend and that this will contribute overall, negatively, to sea level rise. The GCM’s have expectations about SMB. Which is why this matter is being discussed in this thread.
Now, the paper under discussion is interesting in the sense that it has the worst possible outcome for Warmists…
IF there was a positive SMB trend then Warmists could say, “See, this is completely consistent with the climate models. This reaffirms the IPCC’s position.”
IF there was a negative trend, you could even spin this and say, “Yeah OK the IPCC climate models got it wrong, but just that mean’s *it’s worse than we thought.*”
Instead there is no SMB trend… So Warmists don’t want to talk about this. There is nothing they can say, it’s the worst of all possible outcomes.
So let’s come back to MB. What can we say? Not much. Most papers are hesitant to draw any conclusions on trends because there is not much data there and it’s highly variable. Rignot et al. (2011) did draw a conclusion, but it looks like a fairly shaky one, since most of the MB loss looks like it happened in ’92-93 and not much has really happened since. But because the paper conflates Greenland MB with Antarctic MB, Warmists aren’t looking at the paper carefully or sceptically.

robert,
Have you looked at the southern ocean SST lately:http://bobtisdale.files.wordpress.com/2012/02/13-southern.png
The drop in Southern Ocean SST is likely correlated with expanding sea ice.
Meanwhile Vostok temps have been declining for thirty years as well as cloudiness along with increasing high pressure which translates into decreased snowfall at the center of Antarctica which produces adiabatic downslope winds across the Antarctic Peninsula that produce local warming that is studied with the tunnel vision of AGW proponents that ignores what is happening in the remaining 95% of the continent. The IPCC predicted the SMB would be slightly negative because they believed the sea ice would decrease while the snowfall over the continent would increase due to rising relative humidity. The fact is that just the opposite has occurred. Finally, Robert have you looked at the decline in sea level rise since 1998. It is becoming increasingly more difficult to slice a smaller pie to account for melting land ice and thermal expansion.

>> I wonder how many commenters here ever read the IPCC analysis:”
> Most likely no one.
It seems rather likely that most of you haven’t. Which means you don’t know what you’re arguing against, and explains why you’re fighting strawmen. You appear to be proud of your ignorance.
> The fact that the IPCC is unable to confirm or deny growth or shrinkage
Yes, but try actually *thinking* about that, instead of just writing. You’ve got into your head, somehow, the idea that the IPCC is predicting rapid surface ice loss in Antarctica. And now you realise that you’re wrong.
> http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-7-4-4.html
> Connolley appears to cite the parts of the IPCC that are convenient to his argument but doesn’t cite the parts that are inconvenient.
I was trying to cite the bits that are relevant. You’ve cited a bit about reactions of the SMB to changes in temperature, in the future. That isn’t relevant to the current observations. The hint is that chapter 10 is called “Chapter 10: Global Climate Projections”.
LC> This paper doesn’t say what you think it does people.
Nice to see that someone is awake. For the rest: SMB != MB. The hint is in the letter “S” which stands for “Surface”.
[snip]

[Connolley’s] career as a global warming propagandist has now been stopped, following a unanimous verdict that came down today through an arbitration proceeding conducted by Wikipedia. In the decision, a slap-down for the once-powerful Connolley by his peers, he has been barred from participating in any article, discussion or forum dealing with global warming. In addition, because he rewrote biographies of scientists and others he disagreed with, to either belittle their accomplishments or make them appear to be frauds, Wikipedia barred him — again unanimously — from editing biographies of those in the climate change field.
[source]

Smokey says:
February 21, 2012 at 2:52 am
[Connolley’s] career as a global warming propagandist has now been stopped, following a unanimous verdict that came down today through an arbitration proceeding conducted by Wikipedia. In the decision, a slap-down for the once-powerful Connolley by his peers, he has been barred from participating in any article, discussion or forum dealing with global warming. In addition, because he rewrote biographies of scientists and others he disagreed with, to either belittle their accomplishments or make them appear to be frauds, Wikipedia barred him — again unanimously — from editing biographies of those in the climate change field.

False. It was temporary. His buddies carried on till his re-instatement recently to the Editorial Board. Smoky mirrors.

Brian H,
I was just reminding folks that Connolley was slapped down for unethical behavior. I understand that Wikipedia has a heavy alarmist slant. But for Connolley to be reprimanded and suspended shows that he is the worst of a bad lot. And note that his punishment for devious one-sided censorship was unanimous.
Now that Connolley is back in his censoring position, I think it is our duty to expose the charlatan in the interests of integrity and freedom of speech, which Connolley does his best to subvert with is Stalinesque deleting of everyone who doesn’t agree with his [repeatedly debunked] CAGW Party line.

> And note that his punishment for devious one-sided censorship was unanimous
You keep reading things in there that are absent. There was no finding of censorship. That you’re happy to lie about things that anyone can easily check says little for your opinion of other commenters and readers here.

Connolley links to a Wiki page that would make any normal person’s eyes glaze over in a matter of microseconds. But his protestations don’t matter. What matters is his suspension. That is a fact. You don’t get suspended for being a good guy, you get suspended for wrongdoing. And his suspension was unanimous.
The link I posted stated that Connolley “rewrote biographies of scientists and others he disagreed with, to either belittle their accomplishments or make them appear to be frauds, Wikipedia barred him — again unanimously — from editing biographies of those in the climate change field.”
That is dispicable character assassination by someone who should never be allowed near a keyboard again. Connolley is just getting a tiny taste of what he does to others. The difference is that Connolley was found guilty. The others were innocent. Their only “crime” was having a point of view that Connolley didn’t like. Dispicable, no?

Why is WUWT the best science site? Because it exposes many of us to science we were unaware of. This post with the back and forth discussion of SMB and MB forces me to do some research into the basics of what is being discussed and I increase my knowledge. Thanks to all on both sides, especially those that provide links to help the learning process.

sunsettommy says:
February 20, 2012 at 3:34 pm
//////////////////////////////////////////////
As you point out, warmer air is unlikely to cause much ice loss. Due to the high latitute the sun will always be weak. Liekwise summer will always be short. For the vast majority of the year, conditions will always remain well below freezing.
Significant ice loss could only be brought about by a warmer ocean and of course, most of Antartica is not ocean ice, but land ice.
It is therefore extremely difficult to see what mechanism could bring about large scale ice loss in Antartica.
Accordingly, it is difficult to see how there could be large sea level rise associated ith ice loss from Antartica. Predictions are wholly unrealistic.

Robert says:
Couldn’t the forces acting on the “Dynamic” ice loss be from geothermal activity then, in addition to warm ocean currents?
Wikipedia: (I know) In January 2008 the British Antarctic Survey (BAS) scientists, Hugh Corr and David Vaughan, reported that 2,200 years ago a volcano erupted under the Antarctic ice sheet. This was the biggest Antarctic eruption in the last 10,000 years. The volcano is situated in the Hudson Mountains, close to Pine Island Glacier.[16][17] The eruption spread a layer of volcanic ash (or tephra) over the surface of the ice sheet. This ash was then buried under the snow and ice. Corr and Vaughan were able to map this ash layer using an airborne radar system and calculate the date of the eruption from the depth of burial of the ash. This method uses dates calculated from nearby ice cores.[17] The presence of the volcano raises the possibility that volcanic activity could have contributed, or may contribute in the future, to increases in the flow of the glacier.[18]
In other articles on this same survey, it says the there is likely ongoing activity? Do the models take into account subglacial, and submarine geothermal activity? I’ve also read that there is geothermal activity acting on some of the Greenland Glaciers. These articles are also increasingly difficult to find.

So if it’s not snowing more inland, and the melting is accelerating on the perimeter, where is the water going? Sea level rise has dropped by half in the last five years. OK, groundwater has been replenished–that might explain a year or two. Are the oceans getting colder? That’s what we might expect after a decade of cool surface temperatures.
And we have had almost a century of nearly linear sea level rise. Are we to suppose that anthropogenic forcings and resulting feedbacks have combined to produce this linear rate? Or is this better explained as a natural shift between regimes of equilibrium? This is a hell of a way to run a catastophe. –AGF

Ignoring Connolley’s usual ad hominem attacks, it’s not clear to me either that he has much of a grasp of what the IPCC says on the topic of Antarctica until I pointed it out to him. Of course, it’s his right to effectively say the equivalent of, “Yeah the IPCC is not getting this right but their claims are about the future and the future is not now.” OK, yes, true. But would still be nice to have *some* empirical support detectable over the last 30 years of data even if small…?
And I’m still fascinated by the paper cited by BCC which is the basis of the claim for a massive decline in MB in Antarctica. There is only 4 years of ‘reconciled’ GRACE data there and the inter annual variability is as high as 500 Gt. By that I mean one year shows a net loss of 350 Gt. The following year shows a net gain of 150 Gt. A red line is drawn through this short time period pointing downwards (although no obvious trend appears in the actual graphed data), and the authors of the paper conclude there is a massive accelerating ice loss. After drawing this conclusion they introduce a safety net:
“For the same time period, the acceleration in mass loss from the MBM data is 15.1 ± 12 Gt/yr
2. Both estimates have a large uncertainty because of the short period of observation and the large temporal variability in SMB.”
No kidding.
In fields outside climate science – and in fact in most climate science papers I’ve read – when there is an uncertainty as large as that, you say so, and don’t draw a scary conclusion. It would be very interesting to see what one extra year of data does to their results. My suspicion would be that it would significantly change their calculated trend.

new paper: a new “low”?
22 Feb: Sky News UK: Lowering clouds to combat global warming
Clouds around the world may be falling in response to rising global temperatures and having a cooling effect on global warming, according to analysis of satellite data by Auckland University scientists.
The first 10 years of data from the NASA Terra satellite, which uses nine cameras at different angles to produce a stereo image of the world’s clouds, shows their average height has lowered by about 1 per cent, or 30 to 40 metres.
Most of the reduction was due to fewer clouds occurring at very high altitudes, says the study, published in the journal Geophysical Research Letters…
‘We don’t know exactly what causes the cloud heights to lower but it must be due to a change in the circulation patterns that give rise to cloud formation at high altitude,’ Prof Davies said…
‘If cloud heights come back up in the next 10 years we would conclude that they are not slowing climate change,’ Prof Davies said.
‘But if they keep coming down it will be very significant.’http://www.skynews.com.au/eco/article.aspx?id=721052&vId=

Unfortunately, in your quote from the study above, someone left out a minus sign from the actual study. How did this happen? Your quote above:
“The estimated SMB
trend, integrated over the ice sheet, equals 3+/-2 Gt/y^-2”
The actual quote from the study:
“The estimated SMB
trend, integrated over the ice sheet, equals – 3 +/-2 Gt/y^-2”
___
That little minus sign before the 3 means something, and its a shame it was lost when posted here on WUWT. It means, even within the range of error, Antarctic ice mass was declining somewhere between -5 and -1 GT/yr^2, (just as Grace satellite data showed as well).

@R Gates:
It means, even within the range of error, Antarctic ice mass was declining somewhere between -5 and -1 GT/yr^2, (just as Grace satellite data showed as well).
=================================
Except the range of error is obviously huge, which the authors of the paper admit to themselves. Only 4 years of GRACE data is used, the inter annual variability is enormous, and once you look at the rest of the data you actually see it’s basically flat except for 17 years except for the start year of the analysis.
Doesn’t mean the paper is wrong. We need more data. It’s just hard to see how one could draw any sort of solid conclusion out of that data in a fair and balanced way. My political observation here is if sceptics published a paper along similar lines, Warmists would be calling the authors every name under the sun. The question marks in the analysis would be stark and immediate to them.

JJ says:
February 20, 2012 at 3:18 pm
Brian H says:
“Note that the final number given is for an increase, though it is not statistically significant.”
If it had been a decrease, that would have been the title of the paper and the headline of the press release. “Not statistically significant” would have been buried in the fine print and qualified with “but only just”.
Unfortunately for your hypothesis the trend was for a decrease, Anthony or whoever copied the text accidentally dropped the minus sign. So in this case your cynicism is unfounded!

Gates – I don’t read every comment on WUWT as you know, I have comments approaching a million now, which is why I have a volunteer moderation staff. But somebody did email me about it this week, and after some quiet time, I finally figured out why it happened. See the update above. Try the experiment with Notepad yourself.
So much for all the nefarious motives people were ascribing to me.
And, it doesn’t change anything.

Anthony Watts says:
March 3, 2012 at 3:03 pmI finally figured out why it happened. See the update above. Try the experiment with Notepad yourself.
Anthony is correct. The minus sign didn’t survive the copy/paste. I should have caught that. My bad. But since there is a link to the actual paper, one can just go and read it.

For permission, contact us. See the About>Contact menu under the header.

All rights reserved worldwide.

Some material from contributors may contain additional copyrights of their respective company or organization.

We use cookies to ensure that we give you the best experience on WUWT. If you continue to use this site we will assume that you are happy with it. This notice is required by recently enacted EU GDPR rules, and since WUWT is a globally read website, we need to keep the bureaucrats off our case!
Cookie Policy